Low write-current magnetic random access memory cell with anisotropy-varied free layers

We propose a magnetic random access memory (MRAM) cell that utilizes field-induced switching and is applicable to high-speed memories. The MRAM cell, called the shape-varying MRAM cell, has three free layers, each having different shapes and functions, and achieves low write-current switching with high thermal stability and high external field robustness. We show analytically that one of the layers contributes to the low write-current switching and another contributes to the thermal stability. We also show the results of a micromagnetic simulation, in which write current of <0.5 mA, write time of <2 ns, energy barrier (ΔE/ kB T) >100, and external field robustness of >32 Oe were obtained.